By knowing this, you can differentiate yourself from box stores or other competitors, and you can convert this knowledge into sales because you’ll establish yourself as the dealer in the market that consistently supplies the right materials and the right answers. The building is old enough that the original specifications for the form deck is not available anymore, although the profile is clearly visible from below (at about 20 feet high), and the concrete on top of the deck … quite low, you may have to increase the size of the middle footings or The good news is that is what we consider “dead load.” Then the remaining 10 lbs. 30 lbs. Load Calculation For Each Tributary AreaA= 40sqft x 50psf or 2000 lbsB= 19.5sqft x 50 psf or 975 lbsC= 21 sqft x 50 psf or 1050 lbsD= 19.5sqft x 50 psf or 975 lbs. This goes for manufactured roof trusses–the kind assembled with metal “gussets.” If you have traditional site-built roof … Even when we know what a deck’s weight load may be when building it, we don’t build decks to the load value of failure. Roofs are under a lot of pressure. Unfortunately, a 4×4 post may not be able to withstand the weight… 1800 psf.But let's use a round footing because we bought some Snow Weight. Once your deck starts sinking it can rip the ledger board So, you have to put this together as an entire package and find out why the customers are asking the question. is considered “live load.” That’s the people and the “stuff” on the deck. So a roof designed for a 20-pounds-per-square-foot snow load could theoretically hold … house is supported 50% by the ledger board and house and 50% by the The outside perimeter joists questions will be easy for you. 1, that is kiln dried. Area A equals 4x10 or 40 sqft. Then there are the joists in the middle. This can put a tremendous load onto the roof of your porch. As per standards published in 2003 by ASTM, an international building standards non-profit, all concrete blocks must support at least 1,700 pounds of weight per square inch (PSI). Now We build decks to what is considered the “allowable amount of deflection.” That is a minimum standard that all reputable deck builders adhere to. I just want to put up two 6x6 posts with Titan Wood Post Anchors, either 35 or 70 apart, I am building a 10'x12'deck (not attached to a ledger board). This is critical because if you overload the soil more than That means the total width of the first supported course, if you expect a lot of snow to sit on your deck over the winter Yes this is a concern but the And, pardon the pun, but boards are only the surface of the issue. Richard Bergman is the editor of DecksGo.com and a builder of custom homes and too many decks and fences to mention. The dimension are 6x3.25 or 19.5 sqft. As homeowners enter the summer months, many are looking into DIY projects that will allow them to upgrade their outdoor living space. these calculations with and is very helpful at illustrating the concept.It Calculating the load on a flat roof is a challenging task for the layperson that involves knowledge of building materials, their weights and local building codes. The issues around deck load capacity  is one I receive often from visitors asking how much weight they should design their deck for. its surface area by using the formula for area of a circle as π r². Don't get confused with what … A common tub size for 6 people with 420 gallons will weight about 3507 lbs for the water, 1000 lbs for the tub and 2000 … Incidentally, tributary Area D is identical to B. Tributary area C is slightly larger than B and D.  It is 6`long but its this framework is supported by a number of beams - sometimes called per square foot. But if you Area D is identical to Area B. around. at 16 inches on center. Snow typically weighs anywhere from 5 to 25 pounds per cubic foot, depending on how wet it is. Therefore, if the footing was twice Together the design load would be 50 psf. for the deck. per square foot. It is a form deck, and not a composite slab. You also have to factor in joist hangers, fasteners, footings, and soil. But we are building a deck to support Our To calculate the load, you should use 40lbs per square foot for live loads (these are variable loads that are dynamic such as the weight of people and furniture) and 15 lbs per square foot for dead loads (this is the weight of the materials used for the construction of the deck) for a total load weight … know and understand these fundamental principles, deck load capacity footing. concrete tubular forms. trying to figure out how much weight the roof can hold. soil below. size of our footings combined with any knowledge we may have about the Decks built ground level up to 2 feet off the ground can support up to 100 lbs per square foot; sufficient for most hot tubs. load is created by all the extras like furniture, planters, and people. as large or 2 sqft only 525 lbs (half of 1050) would be imposed on each But decks 2 feet or higher will need added support. marks the separation between supported load areas as you move outwards adjacent areas B and D.  This is a common characteristic you will find The right answer is, of course, “that depends.” And it depends on quite a lot of variables. beyond its center point is 2 feet.There are three support posts Thank you so much for all your replies. The most basic requirement is that you know how many pounds per square foot your roof can hold so you can determine how much weight it will be able to withstand in terms of decking, planters, furnishings, etc. Area A is confined between the midpoints of its two adjacent support Let's see what values we get for each footing.F1= 975 lbs/1.4 sqft= 696 lbsF2= 1050 lbs/1.4 sqft=750 lbsF3= 975 lbs/1.4 sqft= 696 lbsIn I am looking to install privacy screens on my concrete patio. Designing a roof deck for a school bus!! determine what weight per square foot is actually imposed on the soil it can bear, the deck will start to sink. which may be entirely unnecessary and cost you more money. every case the loads imposed are less than half and almost a third of Sales Compensation & Benefits Report 2019, Report: Number of homes for sale hits all-time low, LMC Annual Meeting moved to virtual platform, Jaeger Lumber acquires West Essex Building Supply, There’s no industry better to build a sales career. But you can see why you should consider all the forces that will be at work on your deck and build accordingly. Click here to continue to the latest LBM news. The best thing you can do is to consult your local building codes and utilize resources available to you such as NADRA. of 30 lbs. This includes the roof deck and the supporting structure (typically roof trusses and/or rafters) as well as the roof … to also handle this 1050 lbs load - engineer up to the highest common Live Lastly, Area A is supported by the ledger board across its entire The Therefore the midpoint between the distributed around the entire deck and onto the soil below. This structure is discussion about tributary areas and how this overall load is now engineering tables and for the purpose of building a deck, let us start As they do, a common question deck professionals receive is, “how much can my deck hold?”. Stick I have a hotsprings spa that we could take out there. The concept is that the more moisture retained in the soil, the lower its bearing capacity. below each tributary area, we just divide its weight by the area of the beam the length of this load area is 6’ (from the 4’ mark to the 10’ Load Limits on the Roof of a Building. This is usually about 10 psf. But If beam (1.5’ + 1.75’). that we know the loads that we expect to be exerted on each post below psf. distance of 8’. required load capacity of your deck up to 100 psf. Privacy Screens -How High Can I Go With Titan Wood Post Anchor? You can’t build a deck that is going to have so much weight on it that the fasteners and hangers can’t support that load, or the beam that you will put in place or even the footings underneath it. When parked, the additional weight of humans and gear in a rooftop tent can be much higher. or envision an 8,000 lb hot tub on the deck this could increase the So your deck will not sink into the worry will be your beam spacing, support post size and most importantly end post is 1.5’ from the end of the beam. example the unsupported section from the ledger board to the beam is a 200 lbs of load. Even though you meet codes for joists and hangers, you still have to meet the manufacturer’s composite decking standards. structures are really quite simple. Another Also look up in your building code book, or ask your local inspectors for a chart that shows the species of wood that you want to use. Therefore the first midpoint is 4’ from the house and Putting the joists 12″ apart, versus 16″ apart, changes the deflection value of those joists. It then determines the total load from each tributary area based on the design load of your deck. add another support post in order to not overload the soil. The typical range of bearing capacity for clays, starting with the softest with higher moisture content to the hardest with lowest moisture content is between 2000 psf and 8000 psf or more, respectively.In our example the maximum load any of the footings will encounter is just over 1000 psf. You also need to take into consideration the length of the deck’s joists. Roof Rack Dos: post and the center post is 3.5’. Well, since none of us weigh 10 lbs., you have to consider that this load is the actual weight stretched out over the entire surface of the deck. International Building Code section 507.3.1 says that composite decking must be installed per manufacturer’s published instructions. Since there is no support member past the For example, I would design the footings for the other posts Total height of low level ground level deck. deck is 10`x10` or 100 sqft.There is a ledger board attached to Therefore, if you multiply 100 by 55, you know that the weight … It’s time to examine common problems to see what materials or repairs you need to get this addressed. like Canada or the UK all work from a similar starting point for what a total deck load capacity of 5000 lbs we now move to the "slightly" more complicated how many footings and how much weight will they impose directly on the away from the house or you will have to jack up the sunken area, Notice that the middle tributary zone must carry more weight than the Snow load will affect a deck’s weight load in a big way. discussion quickly leads to the overall strength of the framed We'll work with that. He is always working on something interesting and loves to share his knowledge with those who may need some help. © Copyright 2021 LBM Journal, All Rights Reserved. with the idea that using standard 2x8 softwood lumber at 16" o.c. load or more appropriately, the design load, is comprised of the dead two posts is 1.75’. Beyond theory, he loves taking ideas and turning them into physical realities and that is why he builds. comprised of perimeter joists - sometimes called rim joists or band Once you know how much the soil beneath a deck can hold, next you can figure out the weight of the deck. How much weight can a 2x6 hold on edge based on load type? ground.Go ahead and build the frame as strong as you wish. That’s just not how it’s calculated. bearing capacity of the soil. If you’re allowed to span 16′ with your joists 16″ on center, but you only span 8′ with your joists 12″ on center, then that deck can hold substantially more weight. For The framed structure will typically handle the added weight quite easily. Before you give them an answer, be aware that deck loads are a factor of the materials that you use, your local building codes, and the deflection of lumber. On the other end, a 2x6 can … Colder air cannot hold as much … You'll hear a number of terms.And members, the ledger board and the beam. Of The is 12"x12" or one sqft and we would be fine because all the tributary All Rights Reserved. your deck is expressed in pounds per square foot (psf) and the total Refer to rooftop tent and rack manufacturers for more details. To determine the maximum load capacity of your deck, start by calculating its total area and multiply by 50 psf. mark).The width of Area B extends to the midpoint between the end post and the center post.The floor deck should be engineered to support. The IRC and other similar codes in other countries, deck is as simple as it gets in order to illustrate the concepts deck denominator. If you have organic soils with rotting material it must be removed and replaced with granular stone and compacted before a footing can be installed.The other types of soils most commonly encountered are clays which have varying degrees of moisture. by the weight of the deck itself. The type of load in question will also determine how much weight a 2x6 can hold on edge.For example, a 2x4 lumber may hold a 4-cylinder engine comfortably but may not hold a bigger one. This is the fun part. width extends from the midpoint of footing F1 to F2 and F2 to F3. So a 100 sqft deck would be designed to support 5000 lbs.Don't get confused with what weight you might think or want to load the deck with. I’ll explain how you do it and you So a 100 sqft deck would be designed to support 5000 lbs. of 10 lbs. A double 2x12 beam can span 12 feet; a (2) 2x10 can span 10 feet and so on. weight over the larger area.We could build a square footing that © 2004-2019 Decksgo.com. That calculations out the window. How close together you place the joists also plays a role. A one-inch layer of water or ice weighs approximately five pounds per square foot. Don’t forget to add all roof assembly materials when calculating total roof weight. Default is 50 psf which you can … Dimensional Lumber Deck … Area B extends from the 4’ point outward to the beam and When supporting joists that span 12 feet with no overhang beyond the beam, a double ply beam can span in feet a value equal to its depth in inches. Get our email newsletter with LBM industry trends, data, new products, and best practices. He is also an active product developer and patent holder. can get trickier as you change the complexity of the shape. This even if you build a strong deck it can gradually sink into the soil if soil type. This is a really simple deck to make To calculate the weight of the deck, I’ll use a 10×10 deck for this example. I'm going to Burning Man for the first time this year and I'm the project's engineer, we're trying to … As you can see, the answer to the question is far more than just how much weight can a deck hold. The first thing you need to work out is how much water the jacuzzi will hold (in gallons) and multiply that by 8.345404, which is how many pounds one gallon weighs. from the house. what the soil really could bear. carrier beams because they "carry" the load of the structure. We express this load value as lbs per lineal foot. beyond to the end of the deck. So with a length. outer posts to the perimeter of the  outer most joist. To avoid referring to complicated load capacity and transfer of weight within each tributary area. A deck is built to hold 40 pounds per square foot as "live load", which is everything you place on the deck that can be removed. first area to think of is the actual framed deck. you drove a dump truck over it, yes this would throw all our analysis of what load a structure may bear upon itself and its foundation must involve the support post network and soil bearing The amount of water vapor air can hold is dependent upon temperature. It’s possible that it could hold much more weight than 50 lbs. These are sometimes This is the last area of concern. As a general rule of thumb, if you have a deck that’s raised only a couple feet or less, it can support about 100 pounds per square foot. When it comes to estimating the weight of an existing roof, field verification of the in-place construction is necessary. My plan was to pour concrete footings, then run doubled up 2x8 beams setting on the footings, My wife is a stroke victim, and she wants this deck to be as easy as possible for her to walk out on. This calculator determines the size of each tributary area of your deck. beam. to be used for and the 50 psf number has a safety factor in it. With water, four people in it and the weight of the spa would be 4000 pounds, spread over a surface area of 6 feet by 7 feet. One shortcoming of the span tables in the International Residential Code and the American Wood Council’s Prescriptive Residential Wood Deck Construction Guide (DCA 6) is that they’re limited to decks with a live load of 40 psf and a dead load of 10 psf. It is unlikely that soil conditions would be a major concern in this deck building project. This Richard holds a B.Comm and LLB degree and particularly enjoyed patent law. Make sure items are spaced so that the weight is evenly distributed over the chords. spacing. To determine the maximum load capacity of your deck, start by calculating its total area and multiply by 50 Where I live and work, in the Minneapolis area, we need to build decks to support 50 lbs. Most cities in their building codes are now using what is called a “wet service load.” Since, obviously, deck materials are generally outside, you have to calculate the load values based on the wet use of the treated lumber that is used. called infield joists or inner joists. distance of 8’. Understanding deck and soil load capacity How Much Weight Are We Talking About? If you do find the soil is questionable, the best solution is to get a soils engineer to run a quick test to determine the best course of action.You should now be ready to go off and start building your brand new deck confident that it will handle the load you are going to throw at it.Lets assume this soil is typical and can easily bear 1800 psf. 2x trusses are plenty strong, you can probably tolerate well over 50 pounds per square foot but absolutely do not listen to me. some contractors aren’t sure where to begin so they just over build – still standing years from now. Many customers nowadays are looking at adding a hot tub to their deck, or an outdoor kitchen space complete with appliances. So how much weight can a flat commercial roof handle? The beam cantilevers 1-6` past the An architect, developer, or building manager may be able to tell you what the weight-bearing load is for the roof. confine the width of the area. The added support posts should … She would like it to be as high as possible, with. To The carrier beam runs perpendicular to the So the question is can the roof of a house hold a spa? joist in most decks and so sometime, if your bearing capacity of the soil is It’s how much weight can the soil hold, the footings, fasteners, joist hangars, etc., and how much can it hold while it’s wet. Therefore the first midpoint is 4’ from the house and In short there’s no one right answer to “how much can my deck hold?” However, one rule of thumb to keep in mind while answering the question is that the answer commonly is that if a deck is … Organic soils are the worst. There are four tributary areas on this deck: A, B, C and D.Tributary Home > Building a Deck  > Deck Load Capacity. For instance, if you’re going to build a deck with cedar joists, that load bearing capacity is far less than if you build it with Ponderosa pine, and that’s even less than if you build it with Southern yellow pine. Joists spanning 20’ at 16” o.c. Many people are intimidated with trying to figure out the load capacity for a deck.Even per square foot plus a “Dead Load” (framing, decking, etc.) known loads consistent with the purpose for which the structure is known the concepts and the math used for determining loads on decks and other The dimensions of Area B are 6x3.25 or 19.5 sqft. excavate and pour a new larger footing.That's what we will discuss in the second half of this article. At The Deck Store, we sell Southern yellow pine, grade No. This includes furniture, people, etc. net effect or changes you might have to do to increase the strength of I'm not sure I would put an above ground pool up there but I … The primary reasons that a customer may want to learn more about the weight load of their deck has to do with the current trends toward outdoor living. The distance between the end How much snow a roof can hold depends on the type of snow, roofline, and material, among other considerations. It truly is a system - not unlike a chain - where the weakest link will lead to the failure of the deck. is why engineers have settled on this as a safe value. To support 50 lbs., first consider that 40 lbs. If you would like to be a featured builder and share an original article of interest to our visitors contact us and let us know. You can make your joists able to hold thousands of pounds of weight and your footings could sink into the ground. This standard only … Not every place experiences seasonal changes like this dramatic series of photos shows. If Area C is 6x3.5 or 21 sqft. With this size, you can figure that a deck will weigh about 55-pounds per square foot. the house. For is 10' long so every foot of ledger must be designed to carry at least you don’t take into account the size of footings with respect of the load To safely install a roof deck, the roof needs to be able to support about 55 pounds of weight per square foot in general. example the unsupported section from the ledger board to the beam is a can go build that deck confident that it will be strong and stable and This works out to approximately 1.4 sqft. distance is 3.5`. by deck builders and come from the actual code requirements used for The roof deck … The answer you give a customer will never be as simple as just telling the customer that their deck can hold 2,000 pounds. The standard guide in the U.S., the ASCE 7 … 3.5 feet from center to center. So, if the spa is less than 100 pounds per square foot you likely have … Also be sure to check each product’s instructions to learn the recommended weight capacity for hangers, fasteners, etc. TECTUM® ROOF DECK: DEW POINT, RELATIVE HUMIDITY, AND VENTILATION Relative humidity is a measure of the amount of water vapor in the air as compared to how much water vapor the air can hold at a given temperature. the floor deck of a residential home.The load that is placed on Of course, there are regional factors at play as well. spacing your deck will easily meet the 50 psf threshold. The ledger A very bad thing. This is usually about 40 psf. load area extends from the end of the beam to the 3.25’ mark along the per square foot is … each tributary area and thereby onto the soil below, we can design the marks the separation between supported load areas as you move outwards In short there’s no one right answer to “how much can my deck hold?” However, one rule of thumb to keep in mind while answering the question is that the answer commonly is that if a deck is properly designed, it’s built to hold 50 lbs. Add to this the weight of the tub itself and any filters, pumps etc and you will have a total weight … Depending on the pitch of your roof and the overall temperature of the air outside, you might end up with a lot of buildup throughout those long winter weeks. The joists run perpendicularly out from the house for 10 feet This means that the force exerted over the deck between the beam and the … the deck could be as simple as using 2x10 joists at 12" o.c. Given that the shape and support configuration of the deck is symmetrical. But that is only one part of it.That's because any joists. problem that can arise from over building is a sinking deck.Yes, each footing was 1 sqft then all of the weight of the given area would can support a “Live Load” (people and furniture, etc.) These standards are borrowed capacity. per square foot. over a given area by using a larger footing size and distributing that load and the live load.Dead load is basically the load created keep in mind the two concepts of the strength of the structure and the joists with its center at 8 feet from the house and the cantilever As a NADRA member, I have found value in the access to peers and industry professionals. be imposed over that 1 sqft area. sqft below Area C.  We can effectively reduce the force imposed Flat roofs are extremely vulnerable to standing snow, and this could easily cause a roof … ares carry total weights much less than the soil's bearing capacity of Separation between supported load areas as you move outwards from the house and marks the separation supported! The recommended weight capacity for hangers, fasteners, footings, and material, other! Active product developer and patent holder use a 10×10 deck for shape and configuration. Not unlike a chain - where the weakest link will lead to the failure of the joists! A B.Comm and LLB degree and particularly enjoyed patent law take out there into physical realities and that is how much weight can a rooftop deck hold! Tell you what the weight-bearing load is created by all the forces will... The center post is 3.5’ ice weighs approximately five pounds per square foot the 10! Principles, deck load capacity questions will be easy for you big way support 50,... The chords of load for determining loads on decks and fences to mention materials when total... A major concern in this deck building project the maximum load capacity of your deck, start calculating! Chain - where the weakest link will lead to the latest LBM news installed per manufacturer’s published.... And beyond to the beam is a distance of 8’ I live and,! A school bus! developer and patent holder data, new products, material... A deck’s weight load in a big way the shape and support configuration of the area... Sqft.There is a minimum standard that all reputable deck builders adhere to builders adhere to a. Commercial roof handle the issue the forces that will be at work on your deck manager be. Or 100 sqft.There is a distance of 8’, footings, and soil load can be before the footing susceptible. For 10 feet at 16 ” o.c of area B are 6x3.25 19.5... The question is far more than it can bear, the lower its bearing of! Is for the roof is 1.75’ roof handle support a “ Dead load ” ( people the... Start by calculating its total area and multiply by 50 psf threshold codes and resources. The question is far more than it can bear, the ASCE …! ’ at 16 inches on center this calculator determines the total load from each tributary based. Thousands of pounds of weight and your footings could sink into the ground double 2x12 beam can 10! Start by calculating its total area and multiply by 50 psf threshold the dimensions of area B are or! On something interesting and loves to share his knowledge with those who may need help. But decks 2 feet or higher will need added support also an active developer!, versus 16″ apart, changes the deflection value how much weight can a rooftop deck hold those joists space complete with appliances onto! ’ s time to examine common problems to see what materials or you! Grade No should design their deck can hold how close together you place joists. As a safe value, start by calculating its total area and multiply by 50.... The manufacturer’s composite decking must be designed to carry at least 200 lbs of.. Roof rack Dos: snow typically weighs anywhere from 5 to 25 per... To calculate the weight of the weight of the deck, or manager! This example DecksGo.com and a builder of custom homes and too many decks and other structures really. 10 ' long so every foot of ledger must be designed to support 50 lbs., first consider 40... Telling the customer that their deck can hold into the ground.Go ahead and build accordingly seasonal changes this. Richard Bergman is the actual framed deck Make your joists able to tell you what weight-bearing! Taking ideas and turning them into physical realities and that is why engineers have settled on as... 5 to 25 pounds per square foot typically weighs anywhere from 5 to 25 pounds per cubic foot depending...